Ultrasonographic measurement of caudal vena cava to aorta ratio during fluid resuscitation of dogs with spontaneous circulatory shock

Abstract

ObjectivesTo describe the change in the caudal vena cava to aorta ratio (CVC:Ao) ratio during fluid resuscitation of circulatory shock in dogs and compare these results with those of the physical examination and blood lactate.Materials and MethodsPerfusion parameters and blood lactate were recorded at admission. An abdominal point‐of‐care ultrasound protocol was performed, during which the caudal vena cava to aorta ratio was measured on the spleno‐renal view. Measurements were performed within 5 minutes before and after a 10 mL/kg crystalloid fluid bolus. Investigators were not blinded to therapeutic interventions.ResultsTwenty‐nine dogs with physical signs of circulatory shock were enrolled. Caudal vena cava to aorta ratios were below reference interval in 28 of 29 dogs. After bolus administration, median caudal vena cava diameter increased by 0.14 cm (0.69 to 0.83 cm) and median aorta diameter increased by 0.03 cm (0.87 to 0.90 cm) and caudal vena cava to aorta ratio returned to within reference range in 65% of dogs (13/29). Bolus administration was associated with an increase in median caudal vena cava to aorta ratio of 0.10 (95% CI=0.05 to 0.16, P=0.0005). Blood lactate did not change significantly. Heart rate and capillary refill time decreased significantly after fluid bolus (heart rate: estimate=−19 bpm, 95% CI=−30 to −8, P=0.002; capillary refill time: estimate=−1.0 s, 95% CI=−1.3 to −0.7, P < 0.0001).Clinical SignificanceIn this population of dogs with circulatory shock, the caudal vena cava to aorta ratio significantly increased after a fluid bolus. Future studies that implement blinding of the outcome assessors are warranted to confirm these findings.

Efficacy of ultrasonographic caudal vena cava to aorta ratios for quantifying canine parvoviral enteritis rehydration

“…In previous reports, the CVC/Ao value was reported to range between 0.9 and 1.32 in healthy dogs. 2,14 In human medicine, it was reported that the diameter of the aorta remains stable during severe hypovolemic shock or dehydration compared with the decrease in the diameter of the inferior vena cava (IVC). 20 However, as previously reported, 11 a decrease in several ultrasonographic CVC/Ao, corresponding to the IVC/Ao in human studies can be observed.…”

“…15 It has been reported that CVC/Ao decreased and reached the reference range 30 min after administration of furosemide at a dose of 2 mg/kg intravenous to eight dogs with hypervolemia due to congestive heart failure. 14 In addition, another study evaluated the correlation between serum lactate concentration and CVC/Ao before and after fluid therapy in 17 dogs with naturally occurring hypovolemic shock. It was reported that there was a significant increase in CVC/Ao values after fluid replacement and no change in lactate levels.…”

“…After the dehydration scores were determined, CVC/Ao measurement was performed with the same ultrasound device (Minday Z60, Shenzhen Mindray Bio‐Medical Electronics Co., Ltd., China) and probe (5–9 MHz convex probe). Imaging position was on the splenorenal view of the “abdominal focused assessment with sonography for trauma” (AFAST) protocol as reported before 16 . As with the AFAST protocol examination, the fur was not clipped.…”

“…After that, the probe was placed at the left flank of the dogs for measurement of CVC/Ao on splenorenal view. It was ensured that the images were adequate when artifacts such as reverberation and acoustic shadowing were absent and the aorta and CVC were visualized in a single frame 16 . The measurements were performed independently by an observer with 9 years of ultrasound experience (C.B.)…”

“…11 It was reported that the evaluation of CVC/Ao in hypertensive dogs is a promising, noninvasive, and repeatable point-of-care ultrasound protocol and more studies are needed. 14,15 This study aimed to describe ultrasonographic CVC/Ao values before and after fluid replacement in a sample of dogs with varying degrees of dehydration due to naturally-occurring canine parvoviral enteritis (CPE), test correlations between this measure and clinical dehydration scores, and determine the clinical efficacy of this measure for fluid therapy follow-up. Hypotheses were that CVC/Ao is a more effective tool than clinical scoring in determining the adequacy of fluid therapy for dehydration in canine parvoviral enteritis and that CVC/Ao is negatively correlated with dehydration severity.…”